This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

In Today's Military, More Than Just Fatigues Are Green

The world's mightiest fighting force also is a leading sponsor of environmentally friendly power systems.

John Edwards | Jun 28, 2007

Garbage is power. At least that's true for Jerry B.
Warner, president of Defense Life Sciences, which
is developing a trash-to-electricity generator. The
fact that the company is working on a "green"
energy technology isn't unusual. What's out of the
ordinary is that Warner happens to be a retired U.S. Army colonel, and his prime customer is his
former employer.

The U.S. military is investigating green technologies—particularly environmentally friendly power-generation systems. This interest in clean
power isn't entirely altruistic, of course. Cutting-edge alternate energy
technologies will help the military move troops and equipment faster and
safer without relying solely on conventional power sources.

"In this instance, it's a case of where the military's needs dovetail very
nicely with the development of alternate energy sources," says Warner.

Waste Not
Warner describes his company's trash-to-electricity generator as a "tactical biorefinery." The system is designed to allow soldiers in the field to
convert leftover food, paper, and plastic into usable power. Approximately
the size of a moving van, the generator rumbles along with a unit as it
moves from place to place.

At startup, the system runs on conventional diesel fuel. As it's fed leftover boxes and plastics, a gasifier heats the materials in a low-oxygen
environment. Within an hour, the system begins generating energy in the
form of low-grade propane gas and methane. Later, as food waste is
poured in, a bioreactor uses industrial yeast to ferment the waste into
ethanol, a "green" fuel. Both the gas and ethanol are combusted in a
modified diesel engine that powers a generator to produce electricity.

"In about 24 hours, we drive the diesel fuel consumption down to the
single digits," Warner says. In fact, Defense Life Sciences developed the
system in association with Purdue University at the military's behest. "It
was an Army-funded program where we were asked to solve two problems
simultaneously," he says.

The first goal was to create energy from available resources during
expeditionary operations, which are typically during a conflict's first six
months. A secondary aim was finding an efficient way to destroy garbage,
known in the military as a unit's "signature." This would effectively remove any
potential clues leftover refuse might provide an enemy.

"We were shooting for a two-fer," Warner says.

A working prototype was delivered to the
Army last December. Warner says the system can also be used for civilian applications. For example, it could be deployed in the aftermath of a hurricane or tornado or at
any location where people are stranded without power. Emergency crews could then use
the machine to turn debris like woodchips
into much-needed electricity, Warner says. It
could also provide supplementary power for
factories, restaurants, or stores.

Triple Threat
Another type of generator, being developed at the University of Florida in
Gainesville, aims to provide an all-in-one
power, water, and refrigeration source for
moving troops
(Fig. 1). The Army-funded
supergenerator links a gas turbine power
plant to a heat-operated refrigeration system. The refrigeration capability makes the
gas turbine more efficient while also producing cool air and potable water. The turbine can run on conventional fossil fuels as well as biomass-produced
fuels or hydrogen.

"It's actually a fairly common kind of refrigeration system, but when
you put it together with a gas turbine engine you wind up with a system
that you could think of simply as a more efficient gas turbine plant," says
William E. Lear, director of the University of Florida's Energy and Gasdynamic Systems Laboratory. Unlike Defense Life Sciences' trash-to-electricity generator, which is the size of a moving van, the school's three-way system can be small enough to fit into a pickup truck's bed.

The system is designed to serve the needs of soldiers serving in
desert environments, like Iraq, where power, cold air, and drinkable
water are almost always in short supply. "\[The military\] would certainly
like to be able to reduce how much water they have to transport to the
front lines," Lear says. "It costs them just as much to transport water as
it does fuel."

Lear points out that gas turbines are a common power generator used in everything from jet engines to power plants. The problem with traditional systems is that they lose efficiency both when not operated at full power and in warm temperatures. Seeking to ease this loss, Lear rerouted the path of gases passing through the turbine, cooling them via heat exchangers.

S.A. Sherif, a University of Florida mechanical
engineering professor and an expert in refrigeration, then tied the system to absorption units, which further
cooled the gases. Users can either tap all the cooling power
to obtain peak efficiency for the turbine or divert some energy
for refrigeration or air conditioning.

Lear says his experiments and computer
models suggest that with all the cooling
directed to the turbine, it will be 5% to 8% more efficient than traditional turbines. With some cooling siphoned for
other purposes, the system can still be 3% to 5% more efficient than
conventional turbines. Additionally, compared with traditional gas turbines, the system maintains its efficiency whether operated at peak or
partial power.

A few percentage points might not seem like very much. But it makes
a spectacular difference when fuel is scarce or expensive, particularly if
refrigeration and water are added bonuses. "Power companies would kill
for a 1% gain," Lear says.

The system, which makes water by condensing the turbine's combustion gases, can produce about one gallon of water for every gallon of fuel
burned. The water would need to be treated to be potable. Untreated, however, it could still be used for cleaning or other purposes. Because the system reuses gases so efficiently, it also has a very low pollution output.

Lear says further research is needed to make the plant more compact
and to enhance its performance. He notes that larger, more powerful
versions could be used in fixed locations as part of the standard power
grid. Power utilities, for instance, could build the plant close to a grocery
store warehouse that requires both electricity and cooling.

Electric Navy
Like most of the world, the U.S. Navy is very interested in developing
electric vehicles. Currently dependent on diesel fuel and nuclear energy
to power its fleet, the Navy is looking forward to the day when it will be
able to run at least some of its vessels off of batteries. To test the concept, the Navy has awarded Altairnano, a ceramic nanomaterial developer and manufacturer, a contract to develop a ship-mountable 1-MW
power station.

"The ship would still be powered by diesel fuel and generators, but the
Altairnano battery would act as the backup," says Alan Gotcher, Altairnano's president and CEO.

Altairnano's battery approach represents a new and safer take on
lithium-ion technology. Since their development, lithium batteries
have been considered too unstable and volatile for use in
vehicles. The problem is that lithium batteries can
explode: the bigger the battery, the bigger the
potential explosion.

Gotcher says his company's NanoSafe battery
eliminates lithium ion's explosive nature by
forming the anode, the part that discharges electrons, out of lithium-titanate spinels (Fig. 2).
These particles comprise two lithium atoms,
three oxygen atoms, and a titanium atom.
Conventional anodes are based on graphite.
Graphite flakes can come loose and react with the electrolyte, the liquid carrying the lithium particles, and start a
thermal runaway reaction. Altairnano's anode, however, is inert.

"It won't interact with the electrolyte," Gotcher says. "We haven't had a single failure of a
cell in any safety tests, and that includes putting a nail through the cell and overcharging it."

Beyond Navy ships, Altairnano's technology promises to help pave the
way for clean-running, better-performing electric cars, trucks, and buses.
Gotcher says it's possible to power a full-sized five-passenger SUV with a
NanoSafe battery (Fig. 3).

"It's very fast, meaning \[the vehicle\] can go from a standing start to 60
miles per hour in eight seconds," Gotcher says. "It has a range of 135
miles, and you can connect it to a rapid-charge station and completely
recharge the battery pack in less than 10 minutes." The battery can also
operate over a wide temperature range, Gotcher notes.

"To our knowledge, we're the only company anywhere in the world who
has titanate spinels being used in batteries," Gotcher says (Fig. 4). "People
are stunned at how quickly these batteries can be charged."

Gotcher believes it's inevitable that the military will increase its sponsorship of green research simply because so many eco-friendly technologies have definable tactical and operational benefits.

"The military has its energy needs, and businesses and consumers
have theirs," Gotcher says. "It's great when these interests can meet in
the area of green technology."